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BIG PHYSICS, BIG QUESTIONS –

Galactic collision – a taste of things to come?

By Kelly Young

NGC 520’s unique shape is a result of a two-galaxy collision – one galaxy’s dust lane can be seen easily in the foreground. Our own galaxy – the Milky Way – will collide with the Andromeda Galaxy in about 5 billion years

(Image: Gemini Observatory)

Two colliding galaxies in the constellation of Pisces may foreshadow the fate of Earth and the Milky Way billions of years from now.

Astronomers spotted the merged galaxies, collectively known as NGC 520, using the Gemini Multi-Object Spectrographs at the Gemini North Observatory on Mauna Kea, Hawaii, US.

“This is quite scary,” says Ian Robson, director of the UK Astronomy Technology Centre. “Since GMOS was installed on the telescope back in 2001 it has taken some amazing astronomical images of very faint, distant galaxies and star forming regions, providing a wealth of scientific data – but this one sends shivers down my spine.”

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The two original galaxies involved in the collision were likely to have been spiral galaxies, much like our own Milky Way and our neighbouring Andromeda Galaxy. In about 5 billion years, astronomers predict that the Milky Way and Andromeda will collide in a similarly spectacular celestial show.

“Nevertheless, it’s amazing to see so far in advance how planet Earth and our own galaxy will ultimately end,” Robson says. “Glad to say I won’t be around when the fireball happens.”

Despite the look of destruction and chaos, the faint red areas in the image may be areas where stars are forming. The clashing galaxies span 150,000 light years across and lie about 100 million light years from Earth.

Prior to 1980, before the two discs could be differentiated, some astronomers suspected that NGC 520 was a single exploding galaxy, not two interacting galaxies.